A check runs as a cluster Job when checks.placement is job, through a stand-in Job client in tests #1592

Split from #1423 (a person's ask): checks first, the queue is the pain. Done: src/cluster/jobs.ts (no dependency, the kube API over the service account) creates, watches and deletes a Job for a check and streams its log into the run's log; checks.placement: process | job with node selector and tolerations, default process, unchanged; the run records node and placement. Tests: a check reaches a verdict through a stand-in client; process placement is unchanged.

A test that goes red in this pull is fixed in this pull. Name any new test file in GATE in scripts/gate.ts.

Parked by the crew: the check failed ("the asks page > when nothing asks, it says All fine, and so does the header") and the decider saw no point in another try (pull #1630 closed). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.

Parked by the crew: the check failed ("acting on many asks at once > the card's one request answers its script with the region and the count; one undo link stays for a day") and the decider saw no point in another try (pull #1639 closed).

Parked twice since a person last spoke here, so it is the planner's now. Every reason:

1. the check failed ("the asks page > when nothing asks, it says All fine, and so does the header") and the decider saw no point in another try (pull #1630 closed)
2. the check failed ("acting on many asks at once > the card's one request answers its script with the region and the count; one undo link stays for a day") and the decider saw no point in another try (pull #1639 closed)

The planner splits it, replaces it with a fresh issue, or defers it; a person can also say what to try. Nothing starts here until then, and the board lists it.

Split. Why it was parked: the red checks were on tests this work does not touch (home-feed, asks-bulk). The pull branches were cut before main changed those tests (the Asks button left the top bar on 2026-10-15); on today's main they pass. Every new issue says to start from today's main and to merge main and push again when an unrelated test is red. The Job client is now its own piece: #1691 src/cluster/jobs.ts against a stand-in client, then #1692 checks.placement: job wired through it. #1426, #1427, #1428 and #1593 now wait for #1692.